From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-bk0-f46.google.com (mail-bk0-f46.google.com [209.85.214.46]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id B1DD3200666 for ; Sat, 9 Feb 2013 10:15:15 -0800 (PST) Received: by mail-bk0-f46.google.com with SMTP id j5so2128978bkw.33 for ; Sat, 09 Feb 2013 10:15:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; bh=aO7yNgtpuYJ3NG+xbw+I4i7gyYSTTb+Du88c4xhisGE=; b=gvDt5Yfoq0IBj8ZMhRA9KJ4eqmBWHns9crPk/xWmLoX3SE9EXSgF5U0jV8+0YO2fhH cHu9KVLHKKX0wkHk8gVKVVuY/aFKVArTXwQJ8tGE42uhFV6iCFgIs0q1HFgmUp5cZtKz BPXniNFNwJWyotsMuqt8wkBVCmw7RITdmnwuCfPauiMYdlXeRrCyii2osIY+ZeJ0QMnu XEx9EaSZJuKjiOk3vKVOYd/0dPyt88necumihatqoNJiL6wQhJHDStQ/h5xL5TKkeRXs I+YNTixAuu/Y8Jpp4LF9UPzSLZH0wFsMJTGqqbF02zN8Zju4cg/ZTYlBma4TIyUxzBeC FzqA== MIME-Version: 1.0 X-Received: by 10.204.147.130 with SMTP id l2mr2522368bkv.127.1360433713427; Sat, 09 Feb 2013 10:15:13 -0800 (PST) Received: by 10.204.50.150 with HTTP; Sat, 9 Feb 2013 10:15:13 -0800 (PST) Received: by 10.204.50.150 with HTTP; Sat, 9 Feb 2013 10:15:13 -0800 (PST) In-Reply-To: References: Date: Sat, 9 Feb 2013 20:15:13 +0200 Message-ID: From: Jonathan Morton To: Forums1000 Content-Type: multipart/alternative; boundary=0015174c430e3ab70204d54ea8be Cc: bloat Subject: Re: [Bloat] I am unable to pinpoint the source of bufferbloat X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 09 Feb 2013 18:15:16 -0000 --0015174c430e3ab70204d54ea8be Content-Type: text/plain; charset=ISO-8859-1 Latency caused by bufferbloat always appears at the bottleneck device. Usually that is the modem, and you've given no alternative that it could plausibly be. The modems you mention are slightly different model numbers, but that can hide substantial differences in internal configuration. For a typical drop-tail queue, the induced latency under load is the size of the buffer divided by the speed of the link draining it. Assuming both modems have a 4Mbit uplink, 550ms is consistent with a 256KB buffer, and 220ms is consistent with a 48KB buffer - neither of which would seem excessively large to a modem builder who hasn't heard of bufferbloat. However with a shared cable infrastructure, it is possible that the uplink is constrained by other users on the same segment, which will skew this calculation. To cure it without modifying the modem, you need to move the bottleneck to a point where you can control the buffer. You do this by introducing traffic shaping at slightly below the advertised modem uplink speed on one of your own machines and directing all upstream traffic through it. - Jonathan Morton On Feb 9, 2013 7:27 PM, "Forums1000" wrote: > Hi Jonathan and Dave > > My entire LAN-network is gigabit. My cable subscription is 60 megabit down > and 4 megabit up. > Now, both my routers' WAN-port and the cable modems' LAN port are also > gigabit. The router can route LAN to WAN and the other way around (with NAT > and connection tracking enabled) in excess of 100 megabit. > > Now my cable modem is a Motorola Surfboard SV6120E and hers is a Motorola > Surfboard CV6181E. My upload lag is 550ms and hers is only 220ms. Moreover, > at her place there are Powerplugs in the path limiting her download to 30 > megabit instead of 60 megabit. Yet, the upload lag is much lower than mine. > There, it also did not matter where I ran Natalyzr, the result was always > 220ms of bufferbload. > > Could this still be only the modem? > > > On Sat, Feb 9, 2013 at 10:52 AM, Forums1000 wrote: > >> Hi everyone, >> >> Can anyone give some tips on how to diagnose the sources of bufferbloat? >> According to the Netalyzr test at http://netalyzr.icsi.berkeley.edu/, I >> have 550ms of upload bufferbloat. I tried all kinds of stuff on my Windows >> 7 laptop: >> >> - For the Intel(R) 82567LF Gigabit Network Connection, I put receive and >> transmit buffers to the lowest value of 80 (80 bytes? 80 packets? I don't >> know). I also disabled interrupt moderation. >> Result? Still 550ms. >> - Then I connected my laptop directly to my cable modem, bypassing my >> Mikrotik 450G router. Result? Still 550ms of bufferbloat. >> - Then I put a 100 megabit switch between the cable modem an the laptop >> (as both cable modem and Intel NIC are gigabit). Result? Still 550ms of >> upload bufferbloat. >> >> I'm out of ideas now. It seems I can't do anything at all to lower >> bufferbloat. Or the Netalyzr test is broken?:-) >> >> many thanks for your advice, >> Jeroen >> >> > > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > > --0015174c430e3ab70204d54ea8be Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

Latency caused by bufferbloat always appears at the bottleneck device. U= sually that is the modem, and you've given no alternative that it could= plausibly be. The modems you mention are slightly different model numbers,= but that can hide substantial differences in internal configuration.

For a typical drop-tail queue, the induced latency under load is the siz= e of the buffer divided by the speed of the link draining it. Assuming both= modems have a 4Mbit uplink, 550ms is consistent with a 256KB buffer, and 2= 20ms is consistent with a 48KB buffer - neither of which would seem excessi= vely large to a modem builder who hasn't heard of bufferbloat. However = with a shared cable infrastructure, it is possible that the uplink is const= rained by other users on the same segment, which will skew this calculation= .

To cure it without modifying the modem, you need to move the bottleneck = to a point where you can control the buffer. You do this by introducing tra= ffic shaping at slightly below the advertised modem uplink speed on one of = your own machines and directing all upstream traffic through it.

- Jonathan Morton

On Feb 9, 2013 7:27 PM, "Forums1000" &= lt;forums1000@gmail.com> wro= te:
Hi Jonathan and Dave

My entire LAN-network is gigabit. My cable subs= cription is 60 megabit down and 4 megabit up.
Now, both my routers'= WAN-port and the cable modems' LAN port are also gigabit. The router c= an route LAN to WAN and the other way around (with NAT and connection track= ing enabled) in excess of 100 megabit.

Now my cable modem is a Motorola Surfboard SV6120E and hers is a Motoro= la Surfboard CV6181E. My upload lag is 550ms and hers is only 220ms. Moreov= er, at her place there are Powerplugs in the path limiting her download to = 30 megabit instead of 60 megabit. Yet, the upload lag is much lower than mi= ne. There, it also did not matter where I ran Natalyzr, the result was alwa= ys 220ms of bufferbload.

Could this still be only the modem?


On Sat, Feb 9, 2013 at 10:52 AM, Forums1000 <forums1000@gmail.com> wrote:
Hi everyone,

Can anyone give some tip= s on how to diagnose the sources of bufferbloat? According to the Netalyzr = test at ht= tp://netalyzr.icsi.berkeley.edu/, I have 550ms of upload bufferbloat. I= tried all kinds of stuff on my Windows 7 laptop:

- For the Intel(R) 82567LF Gigabit Network Connection, I put receive an= d transmit buffers to the lowest value of 80 (80 bytes? 80 packets? I don&#= 39;t know). I also disabled interrupt moderation.
Result? Still 550ms.<= br> - Then I connected my laptop directly to my cable modem, bypassing my Mikro= tik 450G router. Result? Still 550ms of bufferbloat.
- Then I put a 100= megabit switch between the cable modem an the laptop (as both cable modem = and Intel NIC are gigabit). Result? Still 550ms of upload bufferbloat.

I'm out of ideas now. It seems I can't do anything at all to lo= wer bufferbloat. Or the Netalyzr test is broken?:-)

many thanks for = your advice,
Jeroen



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Bloat mailing list
Bloat@lists.bufferbloat.net<= /a>
= https://lists.bufferbloat.net/listinfo/bloat

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